Fix break/continue when switch is nested inside loop (#11802)

* Fix break/continue when switch is nested inside loop

* merge retCheck

packages/babel-plugin-transform-block-scoping/src/index.js

@@ -844,55 +844,26 @@ class BlockScoping {
 
   buildHas(ret: string) {
     const body = this.body;
-
-    let retCheck;
     const has = this.has;
-    const cases = [];
-
-    if (has.hasReturn) {
-      // typeof ret === "object"
-      retCheck = buildRetCheck({
-        RETURN: t.identifier(ret),
-      });
-    }
 
     if (has.hasBreakContinue) {
       for (const key of Object.keys(has.map)) {
-        cases.push(t.switchCase(t.stringLiteral(key), [has.map[key]]));
-      }
-
-      if (has.hasReturn) {
-        cases.push(t.switchCase(null, [retCheck]));
-      }
-
-      if (cases.length === 1) {
-        const single = cases[0];
         body.push(
           t.ifStatement(
-            t.binaryExpression("===", t.identifier(ret), single.test),
-            single.consequent[0],
+            t.binaryExpression("===", t.identifier(ret), t.stringLiteral(key)),
+            has.map[key],
           ),
         );
-      } else {
-        if (this.loop) {
-          // https://github.com/babel/babel/issues/998
-          for (let i = 0; i < cases.length; i++) {
-            const caseConsequent = cases[i].consequent[0];
-            if (t.isBreakStatement(caseConsequent) && !caseConsequent.label) {
-              if (!this.loopLabel) {
-                this.loopLabel = this.scope.generateUidIdentifier("loop");
-              }
-              caseConsequent.label = t.cloneNode(this.loopLabel);
-            }
-          }
-        }
-
-        body.push(t.switchStatement(t.identifier(ret), cases));
-      }
-    } else {
-      if (has.hasReturn) {
-        body.push(retCheck);
       }
     }
+
+    // typeof ret === "object"
+    if (has.hasReturn) {
+      body.push(
+        buildRetCheck({
+          RETURN: t.identifier(ret),
+        }),
+      );
+    }
   }
 }

packages/babel-plugin-transform-block-scoping/test/fixtures/general/for-break-continue-closure/exec.js

@@ -0,0 +1,15 @@
+expect(() => {
+  for (const a of [1]) {
+    switch (true) {
+      case true: {
+        const b = 1;
+        () => b;
+        if (true) break;
+        continue;
+      }
+      case false: {
+        throw new Error("unreachable");
+      }
+    }
+  }
+}).not.toThrow();

packages/babel-plugin-transform-block-scoping/test/fixtures/general/for-break-continue-closure/input.js

@@ -0,0 +1,13 @@
+for (const a of [1]) {
+  switch (true) {
+    case true: {
+      const b = 1;
+      () => b;
+      if (true) break;
+      continue;
+    }
+    case false: {
+      throw new Error("unreachable");
+    }
+  }
+}

packages/babel-plugin-transform-block-scoping/test/fixtures/general/for-break-continue-closure/output.js

@@ -0,0 +1,25 @@
+for (var a of [1]) {
+  switch (true) {
+    case true:
+      {
+        var _ret = function () {
+          var b = 1;
+
+          (function () {
+            return b;
+          });
+
+          if (true) return "break";
+          return "continue";
+        }();
+
+        if (_ret === "break") break;
+        if (_ret === "continue") continue;
+      }
+
+    case false:
+      {
+        throw new Error("unreachable");
+      }
+  }
+}

packages/babel-plugin-transform-block-scoping/test/fixtures/general/for-break-continue-return/output.js

@@ -1,5 +1,5 @@
 (function () {
-  var _loop2 = function (i) {
+  var _loop = function (i) {
     fns.push(function () {
       return i;
     });
@@ -15,18 +15,11 @@
     }
   };
 
-  _loop: for (var i in nums) {
-    var _ret = _loop2(i);
+  for (var i in nums) {
+    var _ret = _loop(i);
 
-    switch (_ret) {
-      case "continue":
-        continue;
-
-      case "break":
-        break _loop;
-
-      default:
-        if (typeof _ret === "object") return _ret.v;
-    }
+    if (_ret === "continue") continue;
+    if (_ret === "break") break;
+    if (typeof _ret === "object") return _ret.v;
   }
 })();

packages/babel-plugin-transform-block-scoping/test/fixtures/general/superswitch/output.js

@@ -18,13 +18,8 @@ function foo() {
             return "break";
           }();
 
-          switch (_ret) {
-            case "break":
-              break;
-
-            default:
-              if (typeof _ret === "object") return _ret.v;
-          }
+          if (_ret === "break") break;
+          if (typeof _ret === "object") return _ret.v;
         }
     }
   }